The present invention relates to a scanning type near field interatomic force microscope which observes the surface shape of a substance to be measured by using an interatomic force acting between substances and which at the same time, observes optical characteristics of the substance to be measured in a minute region by a probe made of a light transmitting material.
In a conventional scanning type near field interatomic force microscope, as shown in FIG. 3, a shaft portion of a hook-shaped probe 1 of a light transmitting material is used as a cantilever. The light emitted from an optical source 8 passes through the probe 1, which formed of an optical fiber, and is made to irradiate a sample 2 from the tip thereof. The transmitting light influenced by the optical characteristics of the sample 2 is detected by an optical detector 11 through an objective lens 9 and a reflecting mirror 10. The relative movement between the probe 1 and the sample 2 is performed by an XYZ scanner 12.
The probe 1 is attached to a bimorph 4 for oscillating the tip of the probe 1 in the vertical direction. This is done to prevent the tip of the probe 1 and the surface of the sample 2 from being seriously damaged by the roughness of the surface of the sample 2 when the probe 1 is made to scan the surface of the sample 2 in the horizontal direction.
The bending of the cantilever caused by the interatomic force acting between the tip of the probe 1 and the surface of the sample 2 is detected by a displacement magnifying mechanism comprising an optical lever system 14 by using an optical reflector provided on a portion of the cantilever of the probe 1.
The XYZ scanner 12, bimorph 4, and optical lever system 14 are controlled by a controller 13. Such a scanning type near field interatomic force microscope is disclosed in Japanese Laid-Open Patent Publication No. Hei. 7-174542.
On the other hand, there is a system in which such a cantilever is assembled in a quartz oscillator and the interatomic force is detected by the shift of a resonance frequency of the quartz oscillator, and such an interatomic force microscope is, for example, disclosed in Japanese Laid-Open Patent Publication No. Sho. 63-309803 and No. Hei. 4-102008.
Further, in the field of a near field microscope, there is known a system in which a linear optical fiber having a sharpened tip is used as a probe, and measurement is conducted in the state where the tip of the probe attached to a quartz oscillator is vibrated in parallel with the surface of the sample.
In the conventional scanning type near field interatomic force microscope using light to detect the bending of the cantilever, it must be avoided that the detecting light affects the near field optical measurement. For that purpose, it is necessary to make the wavelength region of the detecting light for detecting the bending of the cantilever differ from the wavelength region of the measuring light used in the near field optical measurement. This is a limitation to the near field optical measurement and mounting of a microscope device.
Further, in the near field optical measurement to detect faint light passing through a minute opening, it is sometimes difficult to avoid the influence of the detecting light for detecting the bending of the probe.
In addition, there is a problem in that the optical system for detecting the bending of the cantilever occupies a part of the space around the probe, so that the arrangement of an optical system for near field optical measurement in a reflecting mode is limited.
Further, in the conventional device, the optical axis of the detecting light for detecting the bending of the cantilever must be aligned with the optical reflector of the cantilever, or the alignment of optical detecting elements must be conducted, that is, the troublesome adjustment operations must be made in order to carry out the measurement.
On the other hand, in the system in which the linear optical fiber probe having a sharpened tip is attached to the quartz oscillator and measurement is carried out in the state that the tip of the probe is made to vibrate in parallel with the surface of the sample, there is a defect in that when a very rough sample is measured, the tip of the probe is apt to be damaged. Further, there is a defect in that the space above the surface of the sample is occupied by the quartz oscillator for oscillating the probe, so that the conventional system is disadvantageous in reflective measurement and observation for positioning of the sample.